Wide-field High-speed Spectral Domain Polarization Sensitive Optical Coherence Tomography

Abstract

 

Purpose:

 

To test the performance of a novel wide field high speed spectral domain polarization sensitive OCT (PS-OCT) instrument for retinal in vivo imaging in healthy and diseased eyes.

 

Methods:

 

A newly developed PS-OCT system operating with an A-scan rate of 70 kHz and with a maximum scanning angle of 40°x40° is introduced. The high imaging speed can be translated either into a shorter measurement time or in a more densely sampled 3D volume. Furthermore, the instrument shows, in comparison to previous PS-OCT instruments, a lower sensitivity decay with depth (~ 8 dB over 1.8 mm) which simplifies patient alignment and yields a better penetration into deeper retinal layers. Moreover, an averaging of several B-scans recorded at the same location becomes possible even without the use of an eye-tracker. The polarization sensitive data was compensated for the influence of the anterior segment birefringence and en face maps of retardation, birefringence and RNFL thickness were generated. Additionally, the polarization scrambling character of the retinal pigment epithelium (RPE) was used to segment it solely based on its intrinsic tissue properties.

 

Results:

 

Different scanning protocols were evaluated and the image quality was found to be superior to previous PS-OCT instruments. The Figure shows an example of wide angle en-face maps (intensity and retardation) and representative averaged B-scans of the fovea regions. Up to now 26 patients with either AMD or glaucoma have been measured.

 

Conclusions:

 

The image quality of the newly developed PS-OCT instrument was found to be substantially better than that of previous PS-OCT instruments. Therefore the applicability of PS-OCT in patients will be extended.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retinal pigment epithelium • nerve fiber layer